hydrogen powered marine engine

Discussion in 'Boat Design' started by Bryan Campbell, Feb 24, 2006.

  1. marshmat
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    marshmat Senior Member

    From the Janesville Gazette article mentioned in post #43:
    Let me start by saying that I am not making a judgement on the system itself, or on the perceived and/or actual benefits.

    I can say for sure that the explanation given by Dan Lutz in the article, quoted above, is incorrect. The error comes from mixing up two different efficiency values used in engine design.

    The 20% figure quoted for a gas engine is either the brake or indicated thermal efficiency- ie, what fraction of the heat energy released during combustion ends up as mechanical work (total work for indicated, total less internal friction, pumping losses, etc. for brake). No amount of engineering genius can possibly make this value 100%; it's a function of the thermodynamic cycle, not the type of fuel.

    The 100% figure is the combustion efficiency- ie, what fraction of the energy in the fuel ends up as heat. This value rarely drops below 95% even for a poorly running engine. And unburned fuel emissions have been regulated for years; modern 4-stroke engines simply do not release large amounts of unburned fuel.

    Thus, the explanation given in the article is incorrect.

    However, that does not mean that the system does nothing:

    Hydrogen has an extremely high burn velocity, and will burn at much leaner ratios than most hydrocarbons. Thus, it is possible that the addition of trace amounts of hydrogen serves to cause a rapid, hot flame to move away from the ignition point faster than the main flame front, igniting the hydrocarbon fuel as it goes. The combustion time would thus be shortened, which would tend to increase the peak pressure, and thus the IMEP, BMEP and torque, for a given RPM and fuel mass. A higher peak pressure leads to a higher peak temperature and higher thermal efficiency. It is also conceivable that this would allow for a leaner mix, although that would cause NOx problems and screw up a catalytic converter if one is fitted.

    So improving efficiency by injecting small amounts of hydrogen to accelerate combustion is plausible and possibly beneficial. "Run your car on water", ie. using hydrogen generated by on-board electrolysis as the primary or only fuel, is clearly not plausible.

    The question thus becomes: Given a particular engine running on hydrocarbon fuel, does the increase in power output that results from a faster combustion speed offset the 0.2 to 0.3 kW that is required to generate trace amounts of hydrogen? And by how much?

    The way to find out would be to use an engine set up for dyno testing with an in-cylinder pressure transducer. Comparison of the cylinder pressure curves running on pure gasoline and with a few percent (say up to 10%) hydrogen blended in would certainly reveal exactly what benefit, if any, the concept has.


    Edit- found the attached paper from Jacob Wall of the University of Idaho on these hydrogen-boosted hydrocarbon systems. It's a literature survey, there are several glaring errors and doesn't look like it's been through a review board, but interesting nonetheless.
     

    Attached Files:

  2. Boston

    Boston Previous Member

    interesting
    I came up with a cost of nearly half per btu for wood pellets when compared to diesel
    if this system can enhance a diesel engine by an efficiency factor of 2x then it begins to get my attention
    but
    the steam system is dramatically simpler and cheaper both to purchase and to maintain
    so hydrogen's got a ways to go before I start seriously considering it

    hardest part about the steam system is converting boilers designed to burn fuel oil to burning pellets
    shouldn't be to hard but I do foresee a few problems keeping a pile of pellets burning while Im rocking and rolling on the open sea

    choke cough spit
    um shouldn't be to hard to keep the boilers lit
     
  3. clmanges
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    clmanges Senior Member

    Off the topic of hydrogen as fuel, but the electrolysis reminded me of something else -- MHD (magneto-hydro-dynamic) drives. No moving parts, runs on electricity, would work naturally with sea water, since it contains a lot of electrolytic ions.
    You have two plates, oppositely charged, spaced apart fore and aft; the ions are electrically propelled. IIRC, this was proposed as a silent drive system for submarines, but I don't think it got very far. Haven't heard anything about it in a while.
     
  4. marshmat
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    marshmat Senior Member

    I built a small lab-scale MHD pump a few years ago. It did work, just not very well. They are almost astonishingly simple, in principle. Just a honkin' big magnetic field (a few tesla, to get any decent thrust- ie, like the magnet of a medical lab's MRI scanner would be ideal), a big electric current running through (yes, through) the water perpendicular to the field, and the resulting thrust is proportional to the cross product of the electric and magnetic fields.

    In practice, there are problems. One is that you need a really, really big magnet- our little resistive electromagnet could only give a quarter-tesla or so. That's enough to get a hammer or screwdriver stuck pretty tightly, but not enough for a good MHD. You need a supeconducting coil for it to really work well. The other problem is that, at least in our test model, most of the electricity ended up electrolyzing the water and the salt instead of creating useable thrust. So we had a fair bit of hydrogen, solid calcium oxide, and chlorine gas coming out.

    It's an easy thing to make; if anyone wants to play with a benchtop-scale one, start a new thread on that topic and PM me....
     
  5. Boston

    Boston Previous Member

    sounds like red October stuff
    very cool though
    there are a couple of guys playing with devices that use surface tension to propel craft with as well
    I think I posted it in this thread somewhere
    B
     
  6. plebusmaximus
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    plebusmaximus Junior Member

    Hydrogen is very hard to store as a fuel. It is a highly explosive gas.(scary in boats)

    Something like a Browns gas, created from Saltwater via electricity generated by wind and solar would be interesting.

    Still it takes a lot of electricity to produce on demand Browns gas.
     
  7. martinworswick
    Joined: Sep 2008
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    martinworswick Junior Member

    i heard about using hydrogen as a fuel supplement a while ago for use it auto engines, after doing my research i discovered that (don't laugh as i know its obvious when you stop to think) but an alternator only produces electricity when required so there is no spare voltage floating around just waiting to produce hydrogen for you.
    there are also plenty of video's on youtube to watch and the amount of gas being produced doesn't seem to be that much(judging by the bubbles)
    when i'm driving at a 100 km/h my engine is doing around 2700 rpm- thats around 6500 litres of mixture going the engine every minute, what sort of percentage of gas do you need in the engine to make a difference? and not only does it need to make a difference but it has to overcome the cost of the extra fuel used for the production of electricity.
    i don't see it personally.
    when your electricity is free from solar wind etc it may be possible but i also stumbled across plenty of warnings about the potential side effects it can have on an engine.
     
  8. Boston

    Boston Previous Member

    Hey Martin, what I found funny was that after researching green alternatives for power yachts I was left with one of the oldest and simplest technologies.

    even sorta runs on water

    steam

    the million dollar question being were do you get the steam. Turns out the cheapest and most environmentally friendly fuel is wood pellets, not only is it half the cost pr btu of diesel but you can make the stuff with a simple and relatively cheap pellet mill out of yard waste from a basic chipper

    sounds nuts or at least it did to me but if you think about it its carbon neutral as well. Rather than be burning some fossil fuel and releasing its carbon sequestered millions of years ago the carbon in wood was sequestered within the atmospheric life span of co2. The point being that the tree removes co2 from the atmosphere and burning the fuel adds what has been removed back, there is no net gain and the system is a closed loop
    carbon neutral

    The only practical application issue is that each btu from pellets has more volume which in a small yacht could be a problem but in the larger vessels isn't

    a sixty foot vessel could hold 7 tons of fuel (each ton taking up 64 cu/ft) firing two boilers which could feed a modern steam engine and generate 200 hp at 1050 ft/lb torque
    more than enough to get that boat up to hull speed and then some
    and
    like an electric motor with steam the torque is available in all engine speed ranges
    depends on the hull form but the range would be about 800 miles

    hole thing is kinda funny cause with all the crazy expensive technologies people try to apply to yachts it would appear that wood pellets are the way to go

    if someone can layout a system that is cheaper more environmentally friendly and generates as much power Ild love to see it
    looks to me like the steam engine is the winner and the wood pellet is carbon neutral cheep and easy make it yourself fuel

    and its without all the fancy embodied energy intensive untried and bound to break down constantly new technologies
    that also
    cost a fortune

    now to design a boiler that will work upside down and sideways
    actually shouldn't be that hard

    cheers
    B

    my favorite part is I could be lazy and rather than make my own I could make a phone call and buy at wholesale bulk pellets for half of what I calculated them at
    I went with retail prices at $225 a ton but if Im buying a tank so to speak of fuel and I carry 7 tons then I can get the wholesale break on my purchase
    makes the fuel now cost 1/4 what diesel would have cost me for the same btu value
    and
    I calculated diesel at $3 a gallon and that was a low ball price thats bound to be going up up up
    so while yard waste is basically free and always will be my cost benefit over diesel is nothing but going up

    another beauty is that you dont actually need a fuel tank
    stuff comes in bags and you could just figure out how often you want to feed the hopper and make a hopper of that size to give you the range and time between filling it
    then all you have is a pile of bags laying in a fuel locker and one saves again on having to buy expensive fuel tanks
    the savings are endless and its dam near funny to think of how simple reliable and old the system is

    one little tricky part
    ok two
    the engines run at ~600 psi and although the system is a closed steam recovery system if it did get loose
    its going to hurt
    that and the boiler really does need to be able to safely operate both sideways and upside down for prolonged periods of time
    did I mention boilers have been known to explode from time to time
    maybe I should have left that part out

    the comforting part is that I spent $35 dollars on boiler plans so Im sure someone spent a lot of time on safety testing
    har har har
     
  9. erik818
    Joined: Feb 2007
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    erik818 Senior Member

    Boston,
    What would be the weight of a complete steam engine, output power somewhere in the range of 20 - 100 hp? I guess we're streching the subject of the thread, but steam contains mostly hydrogen atoms....
    Erik
     
  10. Boston

    Boston Previous Member

  11. dreamer
    Joined: Nov 2004
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    dreamer Soñadora

    Whenever considering these alternatives, you have to consider entropy. I have already taxed my high school physics knowledge by bringing that up, but you have to understand some very fundamental things about physics and it doesn't take a physicist to understand.

    Consider the universe. Yeah. Big. Even in that context, energy remains constant. You cannot get more out of it than is already there and you can't put more into it then you already have.

    Hydrogen is the most abundant element we know of. Problem is, it's all used up pretty much. There isn't any 'free' hydrogen out there. Consider it the prostitute of the elements. It's shacked up with every other element on the periodic table, and if you want it for yourself well, you're going to have to fork out some serious dough to sleep with her. But, if it makes you feel good then I guess money is no object.

    As for all these other whack job ideas (hydrogen from car battery and saltwater), keep in mind that nothing is that easy. Car batteries have been around a loooong time. Sea water has been around even longer. Had it been that easy, I'm sure some lucky fool would have already figured it out and hydrogen would have come along wayyyy before fossil fuels. Consider mucking about that's required to turn dino droppings into gas and you can see why anything easier would have been tried by now.

    The answer will lie in innovation. It always has. There are many analogies to this. The idea for lightbulbs wasn't anything new, but it took one relentless guy to get it to stick. By the time the Wright Brothers got their plane off the ground, principals of flight had already started to take shape.

    Today, I would guess most of you are reading this on an LCD monitor. Do you remember the first LCD 'screens'? 16 digit calculator readouts where each character was a matrix of 32 little 'pixels'. Your LCD monitor is the EXACT same technology. But innovation has brought it to the level it is now and it didn't really take so long (15years maybe?).

    Electricity is the answer. Not explosions. Energy storage is the new frontier. Innovations in battery systems and ancillary devices such as Ultracapacitors and Supercapacitors are going to make this a reality. The big money is behind it and that's what's been needed for a long time. I can say with a great deal of confidence that my generation will see the day when you can drive a vehicle non-stop coast-to-coast on a single charge. Believe it. When you start seeing companies like Conoco-Philips and Mobil-Exxon dumping money into this industry, you'll know the writing's on the wall. It's already begun.
     
  12. Boston

    Boston Previous Member

    interesting analogy mate
    sounds like you need a girl
    I would not recommend the burlesque show I went to last night
    not sure who ordered up all the fat chicks but there needed to be some kind of warning on the ticket
    as for batteries I certainly hope you are right as I just got done recently calculating my options for batteries in my next build
    the consideration lasted about five minutes
    best
    B
     
  13. dreamer
    Joined: Nov 2004
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    dreamer Soñadora

    yeah, the reason folks shrug off electric power these days is because you need a barge-load of lead-acid or gel or AGM batteries for it to be effective and an enormous array of options for re-charging the suckers. It will be all about storing as much juice in as little space as possible and THAT'S the new frontier IMNSHO.

    If there is a place for hydrogen in the future, it won't be as a fuel to burn, it will be as a source for fuel cells (i.e. 'battery').

    And I don't need a girl thanks. Got four of 'em at home. Please, god, no more.
     
  14. Towboat Ed
    Joined: Apr 2009
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    Towboat Ed Junior Member

    Keep em coming guys. I am learning something from every post. Obviously some very smart people here. I will be getting underway in a day or two. I will be posting my fuel burn figures daily,good or bad. Check out the link(on my website)to the Hydrogen Super Highway...and our "Trade ssociation" ,the IHHOI.,thre is a "Major Player" involved in both..
    www.water4fuel4boats.com
    www.IHHOI.org
    www.hydrogensuperhighway.com
     

  15. dccd
    Joined: Mar 2007
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    Location: south US

    dccd Design director

    Hydrogen power(storage)

    A Caterpillar 3304 has been converted to run off H2, it more common than you may realise. A recent program called NOSH did a conversion for this diesel engine http://www.cdc.gov/niosh/nas/mining/potentialintermediateoutcome26.htm

    H2 Storage is not a big problem for pressure tanks or as in the NOSH project. See: http://www.reuters.com/article/pressRelease/idUS142813 23-Jul-2008 PRN20080723

    Its not perpetual motion to "make" hydrogen off solar or a wave/current driven generator (electrolysis) while docked, using it during much shorter powered runs when sails remain furled if you bother with-em. We are working on H2 fueled yacht conversions and H2 is not viewed as a power source, simply a energy storage system like a battery. Burning the gas its more direct and powerful rather to make it into fuel-cell driven electrons, rectified and into a relatively much heavier electric motor driven propulsion system.

    As for safety, H2 is light unlike battery or fossil fuel fumes, if leaked the H2 rises up and out any vented engine room. Certain chemical binding storage tanks have been shot through without fire or explosion.
     
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